From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5B89EC4332F for ; Fri, 14 Oct 2022 15:33:02 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 8BFB46B0074; Fri, 14 Oct 2022 11:33:01 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 86FAD6B0075; Fri, 14 Oct 2022 11:33:01 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 736A16B0078; Fri, 14 Oct 2022 11:33:01 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0016.hostedemail.com [216.40.44.16]) by kanga.kvack.org (Postfix) with ESMTP id 5E9A66B0074 for ; Fri, 14 Oct 2022 11:33:01 -0400 (EDT) Received: from smtpin25.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay01.hostedemail.com (Postfix) with ESMTP id 2225D1C5E8E for ; Fri, 14 Oct 2022 15:33:01 +0000 (UTC) X-FDA: 80019948162.25.B8CA690 Received: from desiato.infradead.org (desiato.infradead.org [90.155.92.199]) by imf07.hostedemail.com (Postfix) with ESMTP id 8D68E40029 for ; Fri, 14 Oct 2022 15:32:59 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=desiato.20200630; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=tcM8guTF51y4dORNbVL0TNPgqKXsDWO1cxQKagb6RpQ=; b=WVap/vaDDQsosYCxpzXStdd50N Xk2922O8Nbnqsjsb7+6hUodsPGVCrgVKrgsn6NfJbcuv4mwas/y+srH7BfoI2LqFrwhgi10jfsRA5 BF5HbdvfzMysaPdmw34TGJWtYFtfTuuYzrMdn5E4wZaR/0h+CS+5Lnjj8/qEz9fk+crwilALA5lcd 9vyrq/l1kfFZRojAVxnCzyxStxB5YJ4n7DHWVFx7y6nbeh/ctE5/IXQaj3VZTKyKCpdrmYIup4hIp AsBs24qOaZHKyxFCm7DrkIKq/qg/Idd5PdX88EJkUS3LBwmoVyLOnJfA5QcfscgRUwmW1tqkjEaWb ymkHe8ig==; Received: from j130084.upc-j.chello.nl ([24.132.130.84] helo=noisy.programming.kicks-ass.net) by desiato.infradead.org with esmtpsa (Exim 4.94.2 #2 (Red Hat Linux)) id 1ojMfw-003RUm-BQ; Fri, 14 Oct 2022 15:32:40 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits)) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id 248EA30004F; Fri, 14 Oct 2022 17:32:39 +0200 (CEST) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 0D9852C1B0A4D; Fri, 14 Oct 2022 17:32:39 +0200 (CEST) Date: Fri, 14 Oct 2022 17:32:38 +0200 From: Peter Zijlstra To: Rick Edgecombe Cc: x86@kernel.org, "H . Peter Anvin" , Thomas Gleixner , Ingo Molnar , linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, linux-mm@kvack.org, linux-arch@vger.kernel.org, linux-api@vger.kernel.org, Arnd Bergmann , Andy Lutomirski , Balbir Singh , Borislav Petkov , Cyrill Gorcunov , Dave Hansen , Eugene Syromiatnikov , Florian Weimer , "H . J . Lu" , Jann Horn , Jonathan Corbet , Kees Cook , Mike Kravetz , Nadav Amit , Oleg Nesterov , Pavel Machek , Randy Dunlap , "Ravi V . Shankar" , Weijiang Yang , "Kirill A . Shutemov" , joao.moreira@intel.com, John Allen , kcc@google.com, eranian@google.com, rppt@kernel.org, jamorris@linux.microsoft.com, dethoma@microsoft.com, Yu-cheng Yu Subject: Re: [PATCH v2 16/39] x86/mm: Update maybe_mkwrite() for shadow stack Message-ID: References: <20220929222936.14584-1-rick.p.edgecombe@intel.com> <20220929222936.14584-17-rick.p.edgecombe@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220929222936.14584-17-rick.p.edgecombe@intel.com> ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1665761580; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=tcM8guTF51y4dORNbVL0TNPgqKXsDWO1cxQKagb6RpQ=; b=Yvr3FqnEYO3f2v6YD6jZx4/zeZzyasHEUuHDy/giXkPKGEInIfJiKge0M/FhF7f9ZlEp02 Syahmq36W5MpqYxhW2Jah6/bKWpkp5fVrlY2i9ZljErILlVP9lFFjLcEwRuFMgL5RSsymX kOIPKuAoRvsPstF2mWe79jkwfgFqlis= ARC-Authentication-Results: i=1; imf07.hostedemail.com; dkim=pass header.d=infradead.org header.s=desiato.20200630 header.b="WVap/vaD"; spf=none (imf07.hostedemail.com: domain of peterz@infradead.org has no SPF policy when checking 90.155.92.199) smtp.mailfrom=peterz@infradead.org; dmarc=none ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1665761580; a=rsa-sha256; cv=none; b=mX340KndcKqdUBdha8CmYBpXliNj/1yAxp6/i3vZdHYITCCZbxlWY6xTRwKIRRsa/UTMdN PbkR+7Ax2m8g1515PnOORm66emFKsbgk4e5dzIZYLdSBmM8j6pKEloEYy9bVoQtaqNvXco bwF+uHM7F2JkltHhXMlkBOHckjKk9lM= X-Stat-Signature: nodm6atabz76eprs3e8tkpz6igej6iid X-Rspamd-Queue-Id: 8D68E40029 Authentication-Results: imf07.hostedemail.com; dkim=pass header.d=infradead.org header.s=desiato.20200630 header.b="WVap/vaD"; spf=none (imf07.hostedemail.com: domain of peterz@infradead.org has no SPF policy when checking 90.155.92.199) smtp.mailfrom=peterz@infradead.org; dmarc=none X-Rspam-User: X-Rspamd-Server: rspam09 X-HE-Tag: 1665761579-769089 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Thu, Sep 29, 2022 at 03:29:13PM -0700, Rick Edgecombe wrote: > diff --git a/include/linux/mm.h b/include/linux/mm.h > index 8cd413c5a329..fef14ab3abcb 100644 > --- a/include/linux/mm.h > +++ b/include/linux/mm.h > @@ -981,13 +981,25 @@ void free_compound_page(struct page *page); > * servicing faults for write access. In the normal case, do always want > * pte_mkwrite. But get_user_pages can cause write faults for mappings > * that do not have writing enabled, when used by access_process_vm. > + * > + * If a vma is shadow stack (a type of writable memory), mark the pte shadow > + * stack. > */ > +#ifndef maybe_mkwrite > static inline pte_t maybe_mkwrite(pte_t pte, struct vm_area_struct *vma) > { > - if (likely(vma->vm_flags & VM_WRITE)) > + if (!(vma->vm_flags & VM_WRITE)) > + goto out; > + > + if (vma->vm_flags & VM_SHADOW_STACK) > + pte = pte_mkwrite_shstk(pte); > + else > pte = pte_mkwrite(pte); > + > +out: > return pte; > } > +#endif Why the #ifndef guard? There is no other implementation, nor does this patch introduce one. Also, wouldn't it be simpler to write it like: static inline pte_t maybe_mkwrite(pte_t pte, struct vm_area_struct *vma) { if (!(vma->vm_flags & VM_WRITE)) return pte; if (vma->vm_flags & VM_SHADOW_STACK) return pte_mkwrite_shstk(pte); return pte_mkwrite(pte); } ? (idem for the pmd version etc..)